| 主权项 |
1. A fixing device configured to perform a fixing process for fixing a toner image on a sheet carrying unfixed toner when the sheet passes through a fixing nip of a pair of fixing members, the fixing device comprising:
a heating source for heating at least one of the pair of fixing members during the fixing process; a leading-end toner value output part configured to output a leading-end toner value indicating a toner adhesion amount in the toner image carried on a leading area corresponding to an area including a leading end of the sheet in a conveying direction and extending by a predetermined length on a rear side from the leading end; a leading-end fixing value output part configured to output a leading-end fixing value indicating a leading-end fixing temperature necessary to fix the toner image carried on the leading area of the sheet to the sheet, according to the leading-end toner value, and configured to set a higher value to the leading-end fixing value as the leading-end toner value is higher; a leading-end separation value output part configured to output a leading-end separation value indicating a leading-end separation temperature necessary to allow the leading area of the sheet to pass through the fixing nip and separate from the pair of fixing members, according to the leading-end toner value, and configured to set a higher value to the leading-end separation value as the leading-end toner value is higher; and a controller configured to control a heating temperature of the heating source so that a leading-end set temperature at the fixing nip while the leading area of the sheet is passing through the fixing nip becomes equal to or higher than the leading-end fixing temperature, wherein when the leading-end fixing value is lower than the leading-end separation value, the controller performs separation control to control the heating temperature of the heating source so that the leading-end set temperature becomes equal to or higher than the leading-end separation temperature. |
